I just recently beat this game. With a game like Ninja Gaiden I usually will play through a few times changing the difficulty each play through. I want to play on the Warrior difficulty using the Old Film Filter now. So I beat the game on Alcolyte and unlocked the red costume but I read on several websites that I should've also unlocked the Old Film Filter. Is there any special circumstances that I may have missed? I have only collected 26 Crystal Skulls and haven't picked up all the Souls of the Gods and similar items. If there are no special cirscumstances besides beating the game how do I activate it? I'm totally lost here.

Sorry in advance if there is a thread already like this one. I also tried googling my problem before I made this thread.

I did a little bit of research, but I may not be telling you anything new. Try accessing the options menu from in the game. If that doesn't work, you should be able to access it from the options menu from the main menu.